T-joint connector for quantum computing systems

Abstract

The T-joint connector can be useful for connecting one or more flex circuit boards to quantum hardware including one or more qubits. The T-joint connector can include one or more flex circuit boards. Each of the one or more flex circuit boards can include one or more signal lines and one or more spring interconnects including a superconducting material. The one or more spring interconnects can be coupled to the one or more signal lines. The one or more spring interconnects can be configured to couple the one or more signal lines to one or more signal pads disposed on a mounting circuit board associated with the quantum hardware. The superconducting material can be superconducting at a temperature below about 3 Kelvin.

Description

[Technical field]

[0001] Claiming priority

[0001] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 079,241, entitled "T-Joint Connector for Quantum Computing Systems," filed September 16, 2020, which is incorporated herein by reference.

[0002] The present disclosure relates generally to quantum computing systems, and more particularly to T-joint connectors for use in quantum computing systems. [Background technology]

[0003] Quantum computing is a computational method that exploits quantum effects such as superposition of basis states and quantum entanglement to perform certain calculations more efficiently than classical digital computers. In contrast to digital computers, which store and manipulate information in the form of bits, e.g., "1" or "0," quantum computing systems can manipulate information using quantum bits ("qubits"). A qubit can refer to a quantum device that allows for the superposition of multiple states (e.g., data in both "0" and "1" states) and / or the superposition of data itself in multiple states. According to conventional terminology, the superposition of "0" and "1" states in a quantum system can be expressed as, for example,

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number

[0004]

[0004] Aspects and advantages of embodiments of the present disclosure will be set forth in part in the description that follows, or may be learned from the description, or may be learned by practice of the embodiments. [Means for solving the problem]

[0005]

[0005] One exemplary aspect of the present disclosure relates to a T-joint connector for connecting one or more flex circuit boards to quantum hardware including one or more qubits. The T-joint connector can include one or more flex circuit boards. Each of the one or more flex circuit boards can include one or more signal lines and one or more spring interconnects including a superconducting material. The one or more spring interconnects can be coupled to the one or more signal lines. The one or more spring interconnects can be configured to couple the one or more signal lines to one or more signal pads disposed on a mounting circuit board associated with the quantum hardware. The superconducting material can be superconducting at a temperature less than about 3 Kelvin.

[0006] Another exemplary aspect of the present disclosure relates to a method of operating a quantum computing system. The method can include transmitting control pulses to one or more signal lines. The one or more signal lines can be disposed in one or more flex circuit boards. The method can include transmitting the control pulses by the one or more signal lines through the one or more flex circuit boards to a T-joint connector. The method can include transmitting the control pulses through the T-joint connector to a quantum substrate including quantum hardware. The method can include applying the control pulses to perform at least one quantum operation based at least in part on the control pulses, by the quantum hardware.

[0007]

[0007] Another exemplary aspect of the present disclosure relates to a quantum computing system. The quantum computing system can include one or more classical processors. The quantum computing system can include quantum hardware including one or more qubits. The quantum computing system can include a chamber mount configured to support the quantum hardware. The quantum computing system can include a vacuum chamber configured to receive the chamber mount and place the quantum hardware in a vacuum. The vacuum chamber can form a cooling gradient from an end of the vacuum chamber to the quantum hardware. The quantum computing system can include a plurality of flex circuit boards including one or more signal lines. Each of the plurality of flex circuit boards can be configured to transmit a signal by the one or more signal lines through the vacuum chamber. The quantum computing system can include a T-joint connector configured to couple the plurality of flex circuit boards to the quantum hardware. The T-joint connector can include one or more spring interconnects including a superconducting material. The one or more spring interconnects can be coupled to the one or more signal lines. The one or more spring interconnects can be configured to couple the one or more signal lines to one or more signal pads disposed on a mounting circuit board associated with the quantum hardware. The superconducting material may be superconducting at a temperature below about 3 Kelvin.

[0008]

[0008] Other aspects of the present disclosure relate to various systems, apparatus, non-transitory computer-readable media, user interfaces, and electronic devices.

[0009]

[0009] These and other features, aspects, and advantages of various embodiments of the present disclosure will become better understood with reference to the following description and the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the associated principles.

[0010]

[0010] Detailed descriptions of embodiments aimed at those skilled in the art are set forth in the specification, which refer to the accompanying drawings. [Brief description of the drawings]

[0011] [Figure 1] 1 illustrates an exemplary quantum computing system according to an exemplary embodiment of the present disclosure. [Diagram 2]

[0012] 1 illustrates an exemplary quantum computing system according to an exemplary embodiment of the present disclosure. [Diagram 3]

[0013] 1 illustrates an exemplary quantum computing system according to an exemplary embodiment of the present disclosure. [Figure 4]

[0014] 1 illustrates a cross-sectional view of an exemplary flex circuit board according to an exemplary embodiment of the present disclosure. [Diagram 5]

[0015] 1 illustrates a cross-sectional view of an exemplary T-joint connector according to an exemplary embodiment of the present disclosure. [Figure 6A]

[0016] 1 illustrates a perspective view of an exemplary T-joint connector according to an exemplary embodiment of the present disclosure. [Figure 6B] 1 illustrates a perspective view of an exemplary T-joint connector according to an exemplary embodiment of the present disclosure. [Figure 7]

[0017] 1 illustrates at least a portion of an exemplary T-joint connector according to an exemplary embodiment of the present disclosure. [Figure 8]

[0018] 1 illustrates at least a portion of an exemplary T-joint connector according to an exemplary embodiment of the present disclosure. [Figure 9]

[0019] 1 illustrates an example method of manufacturing a T-joint connector according to an example embodiment of the present disclosure. [Figure 10]

[0020] 1 illustrates an example method of operating a quantum computing system including a T-joint connector according to an example embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012]

[0021] Exemplary aspects of the present disclosure relate to T-joint connectors, such as T-joint connectors useful in quantum computing systems with improved signal transmission. One challenge in quantum computing relates to communication between supercooled quantum systems, including quantum hardware (e.g., qubits), and classical computing systems (e.g., binary computing systems). The quantum computing systems can be at least partially controlled by the classical computing systems. The classical computing systems can be kept separate from the quantum hardware. For example, the quantum hardware can be located within a vacuum chamber (e.g., within the vacuum formed by the vacuum chamber) and / or the classical computing systems can be located outside the vacuum chamber (e.g., outside the vacuum formed by the vacuum chamber). The vacuum chamber can provide a temperature gradient between the classical computing system, which can operate at about room temperature, and the quantum hardware, which can operate at about absolute zero (e.g., less than about 10 millikelvin).

[0013]

[0022] Quantum computing systems may require fast and robust communication between classical computing systems and quantum systems (e.g., qubits) to accurately and reliably perform quantum gate operations and / or quantum state measurements. To address this requirement, many systems employ physical signal lines, such as wires, between the classical computing system and the quantum system.

[0014]

[0023] The increased complexity of quantum hardware (e.g., an increased number of qubits) can present challenges with managing the physical signal lines between the classical computing system and the quantum hardware. For example, in some cases, each qubit may require one or more signal lines to transmit signals to and / or from the qubit. For example, the number of signal lines required may increase at least approximately, if not more than linearly, with the number of qubits in the quantum system. For example, in some cases, four signal lines may be required for each qubit, even if some or all of the signal lines are multiplexed. Thus, an increase in the density of quantum hardware can contribute to an increase in the density of signal lines and / or interconnects required between signal lines and components of the quantum computing system, such as the quantum hardware, the ends (e.g., inlets) of the vacuum chamber, feedthroughs for different cooling stages, and / or other components. Additionally, an increase in the complexity of quantum hardware can contribute to greater susceptibility to crosstalk, noise, interference, and the like. Thus, the signal lines must provide sufficient performance relative to other considerations, such as thermal conductivity, noise and / or crosstalk robustness.

[0015]

[0024] As an example, many quantum computing applications employ superconducting qubits that achieve superconductivity, or zero electrical resistance, at temperatures near about absolute zero, i.e., about 0 Kelvin, such as less than about 3 Kelvin. Thus, one challenge associated with quantum computing includes cooling quantum hardware having superconducting qubits to a temperature at which the superconducting qubits achieve superconductivity. For example, in some cases, the superconducting qubits must be cooled to less than about 0.1 Kelvin (K), such as less than about 0.02 Kelvin, i.e., 20 milliKelvin (mK). Typically, the classical computing system may be maintained at a higher temperature (e.g., near room temperature) than the quantum hardware. Physical signal lines may connect to the quantum hardware and thus form a thermal conductor between the classical computing system and the quantum hardware. The physical signal lines may reduce the efficiency of a cooling system (e.g., a cryogenic cooling system) configured to cool the quantum hardware and / or other components of the quantum computing system. Thus, even a single signal line can increase cooling requirements, but as quantum hardware continues to grow in complexity, this problem may become more significant. Thus, the signal lines coupling the quantum hardware to the classical computing system may desirably be physically small (e.g., closely spaced), provide low thermal loads, provide low electrical dissipation, and / or provide other desirable thermal properties.

[0016]

[0025] As another example, it may be desirable to precisely drive quantum bits with signals from signal lines. For example, signal reflections caused by components (e.g., connectors) of the quantum hardware may adversely affect the performance of the quantum hardware. Thus, the signal lines and / or other components (e.g., connectors) may desirably have low reflectivity (e.g., less than about 40 dB). Additionally and / or alternatively, the signal lines and / or other components (e.g., connectors) may desirably provide low distortion (e.g., pulse distortion) so that control signals are precisely transmitted over the signal lines. Low distortion signal lines and / or other components (e.g., connectors) may provide improved precise control signal implementation and / or execution of quantum algorithms in the quantum hardware and / or precise readout from the quantum hardware. Additionally and / or alternatively, the signal lines and / or other components (e.g., connectors) may desirably provide low crosstalk (e.g., less than about 80 dB) between separate signal lines and / or other components. Signal lines and / or other components that provide low crosstalk can provide improved isolated qubit communication, such as by providing that signals on a signal line intended for one qubit are isolated from other qubits, and / or contributing to reduced noise on each additional signal line.

[0017]

[0026] As another example, noise and / or other external factors may affect the performance of the quantum computing system. The signal lines coupling the quantum hardware to the classical computing system may desirably provide little interference in the environment of the quantum hardware. For example, the signal lines may desirably emit little or no heat photons and / or contribute other factors that may disrupt the operation of the quantum hardware. Additionally and / or alternatively, the quantum computing system may desirably block (e.g., by providing filtering) external heat photons, signal noise, and / or other external factors from interfering with the operation of the quantum hardware.

[0018]

[0027] Thus, some quantum computing systems can include one or more flex circuit boards that include one or more signal lines. The flex circuit board can be configured to transmit signals by one or more signal lines (e.g., through a vacuum chamber) to couple one or more classical processors to the quantum hardware. The flex circuit board can include multiple signal lines and can provide significantly improved signal line density in addition to providing improved isolation, reduced thermal conductivity, and / or improved scalability. For example, including a flex circuit board for coupling classical processors to quantum hardware can provide an infrastructure that reliably scales to the increasingly larger qubit counts achieved and / or expected in current and / or future quantum computing systems.

[0019]

[0028] The inclusion of a flex circuit board in a quantum computing system can improve signal communication within the quantum computing system. However, the interface between the flex circuit board and the quantum hardware can present challenges. For example, signal lines may transition between the flex circuit board and signal lines in a mounting substrate, such as a mounting board, that communicates with the quantum hardware. The mounting substrate can include signal traces having a higher signal line density, such as a significantly higher signal line density, than the flex circuit board. This problem can be exacerbated when multiple flex circuit boards interface with a single mounting substrate, further contributing to increased signal line density in the mounting substrate.

[0020]

[0029] In addition to accommodating increased signal line density, the connection between the flex circuit board and the mounting substrate can desirably maintain the accuracy of the signals transmitted through the connection. For example, the connection can desirably have low distortion, crosstalk, reflectivity, etc., that may adversely affect the integrity of the signals communicated through the connection. In addition, many existing connectors are unable to take advantage of the superconducting properties available in certain materials at the temperatures at which the connection between the flex circuit board and the mounting substrate is made. These superconducting properties can be particularly beneficial in quantum computing applications.

[0021]

[0030] Systems and methods according to exemplary aspects of the present disclosure can provide solutions to these and / or other problems. According to exemplary aspects of the present disclosure, a T-joint connector can be provided to connect (e.g., interface between) one or more flex circuit boards and quantum hardware, such as quantum hardware including one or more qubits. For example, the T-joint connector can be configured to couple one or more flex circuit boards to a mounting circuit board associated with the quantum hardware. For example, the mounting circuit board can be or include a board on which the quantum hardware is located, or can be a board that directly communicates with a board with the quantum hardware. For example, the T-joint connector can be configured to vertically connect multiple flex circuit boards to a single mounting circuit board. This can provide a high density interconnect suitable for connecting a large number of signal lines (e.g., from multiple boards) to a single board having a relatively high signal line density while maintaining desirable signal transmission characteristics.

[0022]

[0031] The T-joint connector may include one or more flex circuit boards. Each of the flex circuit boards may include one or more signal lines. In some embodiments, the signal lines may be superconducting signal lines, such as signal lines that include (e.g., are composed of) a superconducting material, such as a material that is superconducting (e.g., experiences superconductivity) at a temperature less than about 3 Kelvin, such as about 1 Kelvin, such as about 20 milliKelvin. For example, in some embodiments, the flex circuit boards may each include at least one ground plane, at least one dielectric layer, and / or one or more signal lines. In some embodiments, the ground planes and / or signal lines may be or include a superconducting material at a temperature less than about 3 Kelvin, such as aluminum, tin, niobium, molybdenum disulfide, BSCCO, etc.

[0023]

[0032] The T-joint connector can include one or more spring interconnects. The spring interconnects can be coupled to signal lines and / or can be in electrical communication (e.g., signal communication) with one or more signal lines. For example, a spring interconnect can be coupled to each signal line. The spring interconnects can couple the signal lines to a mounting circuit board, for example, to one or more signal pads disposed on the mounting circuit board.

[0024]

[0033] In some embodiments, some or all of the spring interconnects may include spring elements. For example, the spring elements may be configured to contact respective signal pads disposed on a mounting circuit board to couple signal lines to the signal pads. In some embodiments, the spring elements may be compressed, bent, retracted, or otherwise positioned such that tension created by mating the T-joint connector with the mounting circuit board establishes firm contact between the spring elements and the signal pads.

[0025]

[0034] The spring interconnects can include a superconducting material, such as a material that is superconducting (e.g., experiences superconductivity) at a temperature of less than about 3 Kelvin, such as about 1 Kelvin, such as about 20 milliKelvin. For example, in some embodiments, the spring elements can include a superconducting material. For example, in some embodiments, the spring elements can be formed of a superconducting material. Additionally and / or alternatively, in some embodiments, the spring elements can include a superconducting coating of a superconducting material. In some embodiments, the superconducting coating can include tin (e.g., as the superconducting material).

[0026]

[0035] In some embodiments, the spring elements may be formed of a non-superconducting material. Additionally and / or alternatively, in some embodiments, the spring elements may include beryllium copper (e.g., BeCu). For example, the spring elements may be formed of a non-superconducting material (e.g., beryllium copper) and coated with a superconducting material (e.g., tin). In this manner, the spring elements may function adequately as springs using a material having the desired mechanical properties (e.g., elasticity, tension, etc.) that may not be superconducting, while the superconducting coating may provide superconductivity, as the coating may be sufficient to provide superconducting properties in the spring interconnects.

[0027]

[0036] In some embodiments, the spring interconnects may be disposed on a surface of a flex circuit board. For example, in some embodiments, the spring elements may be attached to the flex circuit board by signal pads, such as solder pads. The signal pads may provide signal communication with the spring elements. The vias may extend from the signal lines to the signal pads and / or the spring elements. For example, the vias may provide signal communication between the signal lines and the spring elements. In some embodiments, a gap may be provided between the signal pads and the ground plane to separate the ground plane from the signal pads and / or the spring elements.

[0028]

[0037] In some embodiments, the plurality of spring interconnects may be spaced apart across a surface of the flex circuit board. For example, a line of spring interconnects may be coupled to a corresponding line of signal pads in the two-dimensional array of signal pads. In some embodiments, the first flex circuit board may include a plurality (e.g., a first plurality) of spring interconnects spaced apart across a surface of the first flex circuit board in a first direction. Additionally and / or alternatively, the second flex circuit board may be disposed parallel to the first flex circuit board. The second flex circuit board may be spaced apart from the first flex circuit board in a second direction. The second direction may be perpendicular to the first direction. Additionally, in some embodiments, the second flex circuit board may include a plurality (e.g., a second plurality) of spring interconnects spaced apart across a surface of the second flex circuit board in a first direction. For example, a plurality of spring interconnects spaced across a surface of the second flex circuit board can be parallel and / or aligned with a plurality of spring interconnects spaced across a surface of the first flex circuit board.

[0029]

[0038] The spring interconnects can couple the signal lines to one or more signal pads disposed on a mounting circuit board. The mounting circuit board can be associated with the quantum hardware. For example, the quantum hardware can be disposed on the mounting circuit board and / or on a quantum board in direct communication with the mounting circuit board. The mounting circuit board can be a flex circuit board (e.g., formed from one or more flexible substrates) as described herein and / or can be a rigid circuit board. For example, in some embodiments, the mounting circuit board can include at least a ground plane and a dielectric layer. The ground plane and / or the dielectric layer can be flexible and / or rigid. Additionally, a surface of the mounting circuit board opposite the ground plane can include one or more ground pads and / or one or more signal pads. For example, the surface opposite the ground plane can include a two-dimensional array of signal pads. The ground pads can be disposed to provide insulation between the signal pads. For example, the ground pads can be disposed in spaces between the two-dimensional array of signal pads.

[0030]

[0039] In some embodiments, the T-joint connector may be self-aligning. For example, various alignment systems such as shims, tabs, connector hardware, etc. may be used to align the flex circuit board to the mounting circuit board and / or align the spring elements to the signal pads. As an example, the flex circuit board and / or the spring interconnects may be disposed within connector hardware configured to align the T-joint connector to a mating interface on the mounting circuit board. For example, in some implementations, the T-joint connector may include a connector shell configured to receive at least a portion of the flex circuit board within the T-joint connector. The connector shell may be configured to align the T-joint connector (e.g., one or more flex circuit boards) to the mounting circuit board. For example, the connector shell may be received by mounting hardware on and / or proximate to the mounting circuit board that mates with the connector shell to align the flex circuit board to the mounting circuit board.

[0031]

[0040] For example, in some embodiments, the connector shell can include a first connector plate and a second connector plate. The first connector plate can be disposed parallel to and / or spaced apart from the second connector plate to define a volume therebetween. The volume can include, for example, a flex circuit board. For example, the flex circuit board can be disposed between the first connector plate and the second connector plate.

[0032]

[0041] The first connector plate can be secured to the second connector plate. For example, in some embodiments, the first connector plate can be secured to the second connector plate by screws, clamps, bolts, rods, pins, or any other suitable fasteners. In some embodiments, the T-joint connector can include one or more through holes that pass through at least a portion of the T-joint connector. For example, in some embodiments, the through holes can extend through the first connector plate, at least a portion of the flex circuit board, the shim, and / or the second connector plate. In some embodiments, the through holes can extend only through an edge of the flex circuit board (or not through the flex circuit board) to prevent interference with signal lines. The through holes can be configured to receive a rod assembly (e.g., a screw, a rod and a bolt, etc.) to secure the first connector plate to the second connector plate.

[0033]

[0042] In some embodiments, the T-joint connector can include one or more shims. The shims can be configured to space components of the T-joint connector to align and / or separate various components of the T-joint connector. As an example, the shims can be configured to space a first flex circuit board from a second flex circuit board. As another example, the shims can be configured to space the flex circuit boards away from a portion of the connector hardware, such as a connector shell, a first connector plate and / or a second connector plate. In some embodiments, the shims can be or include a non-conductive material.

[0034]

[0043] In some embodiments, one or more tabs can extend from the shim. The tabs can be configured to space the spring interconnects. For example, the shim may space the spring interconnects spaced apart in a direction parallel to the flex circuit board (e.g., spring interconnects on the same flex circuit board) and / or spaced apart in a direction perpendicular to the flex circuit board (e.g., spring interconnects on different flex circuit boards). Additionally and / or alternatively, the tabs can be configured to align the spring interconnects (e.g., spring elements) with the signal pads. For example, tabs can be disposed between adjacent spring interconnects to inhibit the spring interconnects from forming electrical connections with components other than the respective signal pads. Additionally and / or alternatively, the tabs can facilitate aligned contact between the spring interconnects (e.g., spring elements) and the spring pads, for example, by guiding the spring interconnects relative to the respective signal pads when the T-joint connector is mated with a mounting circuit board. In some embodiments, the tabs can be made of the same material as the shim, such as a non-conductive material.

[0035]

[0044] In some embodiments, the T-joint connector can include one or more isolation plates. The isolation plates can be configured to isolate (e.g., electrically isolate) components of the T-joint connector. For example, the isolation plate can be disposed parallel to at least a portion of a flex circuit board, such as between two flex circuit boards and / or between a flex circuit board and connector hardware. For example, the isolation plate can isolate a first flex circuit board from a second flex circuit board and / or isolate the flex circuit board from external interference. Additionally and / or alternatively, an isolation plate can be included between a flex circuit board and a mounting circuit board, for example, parallel to the mounting circuit board. The isolation plate can contact the mounting circuit board (e.g., a ground pad) and / or other suitable ground such that the isolation plate is grounded. In some embodiments, the isolation plate can be attached to a shim. In some embodiments, the isolation plate can be or include a superconducting material, such as a superconducting material below about 1 Kelvin.

[0036]

[0045] As used herein, a "flex circuit board" refers to a substrate including at least one generally planar substrate (e.g., a layered substrate) or other support on which one or more signal lines are formed or disposed and which has flexibility in at least one plane. As used herein, "flexibility" refers to the ability to deform (e.g., be subjected to mechanical stress, etc.) without breaking. For example, a rectangular flex circuit board may be flexible along the largest surface of the rectangular flex circuit board. A rectangular flex circuit board may be flexible and / or rigid along at least a portion of its edges. Flexibility can be achieved as a property of the material (e.g., metals such as copper, copper alloys, niobium, aluminum, dielectric materials, non-metals, polymers, rubbers, etc.) from which the flex circuit board and / or layers of the flex circuit board are formed, by hinging and / or segmenting the flex circuit board (e.g., hinging and / or segmenting rigid portions), and / or in any other suitable manner. The substrate may be strictly planar (e.g., having a cross-section that is substantially linear across its length and width) and / or may be generally planar in that the substrate bends, wrinkles, or otherwise exhibits a shape that is non-linear in at least one cross-section, but generally has a depth that is significantly less (e.g., less than about 10%) than its length and width.

[0037]

[0046] In some embodiments, the flex circuit board can include at least one ground plane. The ground plane can form an outer surface of the flex circuit board, such as an outer surface along a maximum surface. In some embodiments, the flex circuit board can include two ground planes, such as two parallel, spaced apart ground planes. For example, the two ground planes can form both maximum outer surfaces of the flex circuit board. The ground planes can act as electrical isolation layers to isolate signal lines on one side of the ground plane from interfering signals (e.g., from signal lines on other layers, other substrates, the environment, etc.) on the other side of the ground plane. For example, the ground planes can be coupled to earth and / or other suitable grounds.

[0038]

[0047] The ground plane may be or include any suitable conductive material. In some embodiments, the ground plane may be or include a superconducting ground plane including a superconducting material, such as a superconducting material that achieves superconductivity at a temperature less than about 3 Kelvin, such as about 1 Kelvin, about 20 milliKelvin, etc. By way of example, the ground plane may be or include niobium, tin, aluminum, molybdenum disulfide, BSCCO, and / or other suitable superconducting materials. Additionally and / or alternatively, the ground plane may be or include a material having high signal transmission performance characteristics, such as low resistance, low reflectance, low distortion, etc., such that the signal is not substantially altered by passing through the signal line. By way of example, the ground plane may be or include copper, gold, and / or other suitable materials having high signal transmission performance characteristics. Additionally and / or alternatively, the ground plane may be or include a material having desirable thermal properties, such as suitably high and / or low heat transfer, such as, for example, copper, copper alloys, thin superconducting materials, etc.

[0039]

[0048] In some embodiments, the flex circuit board can include at least one dielectric layer. The dielectric layer can be or include any suitable dielectric material, such as a dielectric polymer. In some embodiments, the dielectric layer can be or include a flexible dielectric material. As an example, the dielectric layer can be or include a polyimide. At least a portion of the dielectric layer can be formed on or disposed proximate to at least a portion of an inner surface of the ground plane. For example, in some embodiments, the inner surface of the ground plane can mate with an outer surface of the dielectric layer. Additionally, in some embodiments, the inner surfaces of the two dielectric layers can mate with a signal line disposed therebetween.

[0040]

[0049] The flex circuit board may include one or more signal lines. The one or more signal lines may be disposed on a surface (e.g., an inner surface) of at least one dielectric layer. As an example, in some implementations, the one or more signal lines may be disposed between opposing inner surfaces of two dielectric layers. The signal lines may be or include any suitable conductive material. In some embodiments, the signal lines may be or include superconducting signal lines including superconducting materials such as superconducting materials that achieve superconductivity at temperatures less than about 3 Kelvin, such as less than about 1 Kelvin, less than about 20 milliKelvin. By way of example, the signal lines may be or include niobium, tin, aluminum, molybdenum disulfide, BSCCO, and / or other suitable superconducting materials. Additionally and / or alternatively, the signal lines may be or include materials having high signal transmission performance characteristics. By way of example, the signal lines may be or include copper, gold, and / or other suitable materials having high signal transmission performance characteristics. Additionally and / or alternatively, the signal wires may be or include a material having desired thermal properties, such as, for example, copper, copper alloys, and the like.

[0041]

[0050] In some embodiments, the flex circuit board may include one or more vias. For example, the vias may extend through the ground planes, the dielectric layers, and / or the signal lines. The vias may serve to improve isolation of the signal lines. Additionally and / or alternatively, the vias may serve to couple multiple ground planes and / or to transmit signals between layers of the flex circuit board. In some embodiments, the vias may be plated with a via plate that extends along the vias. In some embodiments, the via plate may be or include a conductive material, such as copper.

[0042]

[0051] A quantum computing system can include quantum hardware in data communication with one or more classical processors. For example, the quantum hardware can represent and / or manipulate information using qubits. A qubit can be or include any suitable quantum device that allows for a superposition of multiple states (e.g., both "0" and "1" states). As an example, a qubit can be or include a unit of a superconducting material, such as a superconducting material that achieves superconductivity at a temperature of about 3 Kelvin or less, such as less than about 20 milliKelvin. In some embodiments, a quantum computing system can include one or more multilevel quantum subsystems, such as a register of qubits. In some implementations, the multilevel quantum subsystem can include superconducting qubits, such as flux qubits, charge qubits, transmon qubits, gmon qubits, etc.

[0043]

[0052] A classical processor may be a binary processor, such as a processor that operates on data represented as a plurality of bits. As an example, a bit may be represented by a voltage difference between a low voltage (e.g., 0V) and a high voltage (e.g., 5V) at a reference point, such as a memory cell, a circuit node, or the like. The low voltage may be associated with a "0" state, and the high voltage may be associated with a "1" state. The classical processor may be configured to control the quantum hardware in addition to any other suitable functions of the classical processor. For example, the classical processor may be coupled to the quantum hardware (e.g., by signal lines included in a flex circuit board according to an exemplary aspect of the present disclosure) and / or configured to send control signals to perform quantum operations using the quantum hardware. As an example, the classical processor may be configured to send control signals that implement quantum gate operations in the quantum hardware (e.g., by a control device). Additionally and / or alternatively, the classical processor may be configured to send control signals that cause the quantum hardware to perform quantum state measurements and / or provide quantum state measurements to the classical processor (e.g., by a readout device). For example, a classical processor can accept measurements of a quantum system that can be interpreted by the classical processor.

[0044]

[0053] Systems and methods according to exemplary aspects of the present disclosure can provide many technical effects and advantages. For example, exemplary aspects of the present disclosure can provide a connector that can desirably provide high density interconnects between multiple flex circuit boards and a mounting circuit board. Additionally, the connector can provide improved signal transmission characteristics through the connector, such as low signal distortion, low reflectance, etc. For example, the use of superconducting materials in the connector can provide performance characteristics suitable for quantum computing applications. For example, the use of superconducting materials can provide little or no contact resistance in the connector.

[0045]

[0054] As used herein, use of the terms "about" or "approximately" in conjunction with a stated numerical value is intended to refer to within 10% of the stated numerical value.

[0046]

[0055] Exemplary aspects of the present disclosure are described herein with reference to quantum computing systems for illustrative purposes. Although systems and methods according to exemplary aspects of the present disclosure may find particular advantages in quantum computing applications, such as quantum computing systems that include flex circuit boards, it should be understood that the systems and methods described herein may be applied to other suitable applications.

[0047]

[0056] Exemplary embodiments of the present disclosure will now be described in further detail with reference to the figures.

[0048]

[0057] FIG. 1 illustrates an exemplary quantum computing system 100. The exemplary system 100 is an example of a system implemented as a classical or quantum computer program on one or more classical or quantum computing devices at one or more locations, in which the systems, components, and techniques described below may be implemented. FIG. 1 illustrates an exemplary quantum computing system that can be used to implement aspects of the present disclosure. Those skilled in the art using the disclosure provided herein will understand that other quantum computing structures or systems can be used without departing from the scope of the present disclosure.

[0049]

[0058] System 100 includes quantum hardware 102 in data communication with one or more classical processors 104. For example, quantum hardware 102 can represent and / or manipulate information using qubits. A qubit can be or include any suitable quantum device that allows for the superposition of multiple states (e.g., data in both "0" and "1" states). By way of example, a qubit can be or include a unit of a superconducting material, such as a superconducting material that achieves superconductivity at a temperature of about 20 mK or less.

[0050]

[0059] Quantum hardware 102 may include components for performing quantum computations. For example, quantum hardware 102 may include a quantum system 110, a control device 112, and a readout device 114 (e.g., a readout resonator). Quantum system 110 may include one or more multi-level quantum subsystems, such as a register of qubits. In some implementations, the multi-level quantum subsystem may include superconducting qubits, such as flux qubits, charge qubits, transmon qubits, gmon qubits, etc.

[0051]

[0060] The classical processor 104 may be a binary processor, such as a processor that operates on data represented as a plurality of bits. As an example, a bit may be represented by a voltage difference between a low voltage (e.g., 0V) and a high voltage (e.g., 5V) at a reference point, such as a memory cell, a circuit node, or the like. The low voltage may be associated with a "0" state, and the high voltage may be associated with a "1" state. The classical processor 104 may be configured to control the quantum hardware 102 in addition to any other suitable functions of the classical processor 104. For example, the classical processor 104 may be coupled (e.g., by a signal line) to the quantum hardware 102 and / or configured to send control signals to perform quantum operations using the quantum hardware 102. As an example, the classical processor 104 may be configured to send control signals that implement quantum gate operations in the quantum hardware 102 (e.g., by the control device 112). Additionally and / or alternatively, classical processor 104 can be configured to send control signals that cause quantum hardware 102 to perform quantum state measurements and / or provide quantum state measurements to classical processor 104 (e.g., via readout device 114). For example, classical processor 104 can accept measurements of quantum system 110 that can be interpreted by classical processor 104.

[0052]

[0061] The type of multi-level quantum subsystem utilized by system 100 may vary. For example, in some cases it may be convenient to include one or more readout devices 114 attached to one or more superconducting qubits, such as transmon, flux, gmon, xmon, or other qubits.

[0053]

[0062] Quantum circuits may be constructed and applied to a register of qubits included in quantum system 110 via multiple signal lines (e.g., signal line 120 in FIG. 2) coupled to one or more control devices 112. An exemplary control device 112 operating on a register of qubits may be used to implement a quantum logic gate or a circuit of quantum logic gates, e.g., Hadamard gates, controlled NOT (CNOT) gates, controlled phase gates, T-gates, multi-qubit quantum gates, coupler quantum gates, etc. The one or more control devices 112 may be configured to operate on quantum system 110 via one or more respective control parameters (e.g., one or more physical control parameters). For example, in some implementations, the multi-level quantum subsystem may be a superconducting qubit, and control device 112 may be configured to provide control pulses on control lines (e.g., signal line 120 in FIG. 2) to generate a magnetic field to tune the frequency of the qubit.

[0054]

[0063] The quantum hardware 102 may further include a readout device 114 (e.g., a readout resonator). Measurement results 108 obtained via the measurement device may be provided to the classical processor 104 for processing and analysis. In some implementations, the quantum hardware 102 may include quantum circuits, and the control device 112 and readout device 114 may implement one or more quantum logic gates that operate on the quantum system 110 via physical control parameters (e.g., microwave pulses) transmitted via wires included in the quantum hardware 102. Further examples of control devices include arbitrary waveform generators from which DACs generate signals.

[0055]

[0064] The readout device 114 may be configured to perform quantum measurements on the quantum system 110 and transmit the measurement results 108 to the classical processor 104 (e.g., over signal line 120 in FIG. 2). Additionally, the quantum hardware 102 may be configured to accept data from the classical processor 104 (e.g., over signal line 120 in FIG. 2) that specifies the physical control parameter values ​​106. The quantum hardware 102 may use the accepted physical control parameter values ​​106 to update the operation of the control device 112 and the readout device 114 on the quantum system 110. For example, the quantum hardware 102 may accept data that specifies new values ​​representing voltage strengths of one or more DACs included in the control device 112 and may update the operation of the DACs on the quantum system 110 accordingly. The classical processor 104 may be configured to initialize the quantum system 110 with an initial quantum state, for example, by sending data to the quantum hardware 102 that specifies an initial set of parameters 106.

[0056]

[0065] The readout device 114 reads the state of an element of the quantum system, such as a qubit, to measure the state of the element (e.g., qubit).

number

number

[0057]

[0066] The system 100 includes a control device 112. The control device 112 can operate the quantum hardware 102. For example, the control device 112 can include a waveform generator configured to generate control pulses according to exemplary aspects of the present disclosure.

[0058]

[0067] In some implementations, the control device 112 may include a data processing device and associated memory. The memory may include a computer program having instructions that, when executed by the data processing device, cause the data processing device to perform one or more functions described herein, such as applying control signals to qubits and / or tunable couplers.

[0059]

[0068] FIG. 2 illustrates an exemplary quantum computing system 100 according to an exemplary embodiment of the present disclosure. As illustrated in FIG. 2, the quantum hardware 102, such as, but not limited to, the quantum system 110, the control device 112, the readout device 114, and / or any other suitable components of the quantum hardware 102 described with respect to FIG. 1, can be disposed within a cryogenic cooling system 130. Additionally and / or alternatively, the classical processor 104 can be disposed outside of the cryogenic cooling system 130. The cryogenic cooling system 130 can be a vacuum chamber or can be disposed within a vacuum chamber. For example, the quantum hardware 102 and / or the signal lines 120 (e.g., a flex circuit board) can be supported by a chamber mount configured to be inserted into a vacuum canister to form a vacuum chamber. For example, the chamber mount can be configured to place the quantum hardware 102 in a vacuum (e.g., formed by a vacuum chamber). The cryogenic cooling system 130 is configured to provide a temperature gradient (e.g., multiple cooling stages) within the vacuum chamber. For example, the temperature gradient can be formed by multiple cryogenic cooling stages, such as stages of a dilution refrigerator. Exemplary stages of a dilution refrigerator can be or include, for example, a first intermediate clamp stage, a first stage pulse tube stage, a second intermediate clamp stage, a second stage pulse tube stage, a stationary stage, an intermediate heat exchanger stage, a mixing chamber stage, a Joule-Thomson cooling stage, a helium liquefaction stage, and / or any other suitable stages of a dilution refrigerator.

[0060]

[0069] Cryogenic cooling system 130 may be configured to cool quantum hardware 102. Additionally and / or alternatively, classical processor 104 is not cooled by cryogenic cooling system 130. For example, classical processor 104 may operate at temperatures near room temperature (e.g., about 300 Kelvin) and / or at temperatures near about 100 Kelvin, whereas quantum hardware 102 may operate at temperatures near absolute zero (e.g., less than about 1 Kelvin) and thus require cooling by cryogenic cooling system 130 to operate effectively.

[0061]

[0070] The quantum computing system 100 can include a signal line 120. The signal line 120 can couple the classical processor 104 to the quantum hardware 102. For example, the classical processor 104 and the quantum hardware 102 can communicate signals, such as transmitting parameters 106 and / or measurements 108 of FIG. 1, in addition to any other suitable signals, so that the classical processor 104 can be coupled to the quantum hardware 102 by the signal line 120. For example, according to an exemplary embodiment of the present disclosure, the signal line 120 can be or include one or more flex circuit boards, such as superconducting flex circuit boards, configured to couple the quantum hardware 102 and the classical processor 104. In general, the signal line 120 includes a physical connection to enable faster and / or more robust communication between the quantum hardware 102 and the classical processor 104. As shown in FIG. 2, the signal line 120 can be at least partially disposed within a cryogenic cooling system 130 to provide coupling to the quantum hardware 102. The increased density of signal lines 120 (e.g., associated with the increased complexity of quantum hardware 102) can present challenges in operating quantum computing system 100, which can be mitigated by the inclusion of a flex circuit board in accordance with an exemplary embodiment of the present disclosure.

[0062]

[0071] FIG. 3 illustrates an exemplary quantum computing system 300 according to an exemplary embodiment of the present disclosure. The quantum computing system 300 can include one or more classical processors 302 and quantum hardware 304 including one or more qubits. The quantum computing system 300 can include a chamber mount 308 configured to support the quantum hardware 304 and a vacuum chamber configured to receive the chamber mount 308 and place the quantum hardware 304 in a vacuum. The vacuum chamber can form a cooling gradient from an end of the vacuum chamber (e.g., cap 307) to the quantum hardware 304. For example, the vacuum chamber can form a cooling gradient from a first temperature, such as room temperature (e.g., about 300 Kelvin), to a second temperature, such as absolute zero (e.g., about 20 milliKelvin), to provide a temperature at the quantum hardware 304 at which the qubits experience superconductivity. In some embodiments, the cooling gradient can be formed by multiple cooling stages that progressively increase and / or decrease the temperature. As an example, the cooling stages can be stages of a stepwise cryogenic cooling system, such as a dilution refrigerator.

[0063]

[0072] The quantum computing system 300 may include one or more signal lines between the classical processor 302 and the quantum hardware 304. According to an exemplary embodiment of the present disclosure, the quantum computing system 300 may include one or more flex circuit boards 306 including one or more signal lines. The flex circuit board 306 may be configured to transmit signals by one or more signal lines through a vacuum chamber to couple the one or more classical processors 302 to the quantum hardware 304. The flex circuit board 306 may include multiple signal lines and may provide significantly improved signal line density in addition to providing improved isolation, reduced thermal conductivity, and / or improved scalability. For example, including a flex circuit board 306 according to an exemplary embodiment of the present disclosure to couple the classical processor 302 to the quantum hardware 304 may provide an infrastructure to reliably scale to the increasingly larger qubit counts achieved and / or expected in current and / or future quantum computing systems. An exemplary flex circuit board that may be employed according to an exemplary embodiment of the present disclosure is shown in FIG. 4.

[0064]

[0073] In some embodiments, some or all of the flex circuit board 306 may include at least one ground plane. The ground plane may form an outer surface of the flex circuit board 306, such as an outer surface along a maximum surface. In some embodiments, the flex circuit board 306 may include two ground planes, such as two parallel, spaced apart ground planes. For example, two ground planes may form both maximum outer surfaces of the flex circuit board 306. The ground planes may act as electrical isolation layers to isolate signal lines on one side of the ground plane from interfering signals (e.g., from signal lines on other layers, other substrates, the environment, etc.) on the other side of the ground plane. For example, the ground planes may be coupled to earth and / or other suitable grounds.

[0065]

[0074] The ground plane may be or include any suitable conductive material. In some embodiments, the ground plane may be or include a superconducting ground plane including a superconducting material, such as a superconducting material that achieves superconductivity at a temperature less than about 3 Kelvin, such as about 1 Kelvin, about 20 milliKelvin, etc. By way of example, the ground plane may be or include niobium, tin, aluminum, molybdenum disulfide, BSCCO, and / or other suitable superconducting materials. Additionally and / or alternatively, the ground plane may be or include a material having high signal transmission performance characteristics, such as low resistance, low reflectance, low distortion, etc., such that the signal is not substantially altered by passing through the signal line. By way of example, the ground plane may be or include copper, gold, and / or other suitable materials having high signal transmission performance characteristics. Additionally and / or alternatively, the ground plane may be or include a material having desirable thermal properties, such as suitably high and / or low heat transfer, such as, for example, copper, copper alloys, thin superconducting materials, etc.

[0066]

[0075] In some embodiments, the flex circuit board 306 can include at least one dielectric layer. The dielectric layer can be or include any suitable dielectric material, such as a dielectric polymer. In some embodiments, the dielectric layer can be or include a flexible dielectric material. As an example, the dielectric layer can be or include a polyimide. At least a portion of the dielectric layer can be formed on or disposed proximate to at least a portion of an inner surface of a ground plane. For example, in some embodiments, an inner surface of the ground plane can mate with an outer surface of the dielectric layer. Additionally, in some embodiments, the inner surfaces of two dielectric layers can mate with a signal line disposed therebetween.

[0067]

[0076] The flex circuit board 306 may include one or more signal lines. The one or more signal lines may be disposed on a surface (e.g., an inner surface) of at least one dielectric layer. As an example, in some implementations, the one or more signal lines may be disposed between opposing inner surfaces of two dielectric layers. The signal lines may be or include any suitable conductive material. In some embodiments, the signal lines may be or include superconducting signal lines including superconducting materials such as superconducting materials that achieve superconductivity at temperatures of about 3 Kelvin or less, such as about 1 Kelvin, about 20 milliKelvin, etc. By way of example, the signal lines may be or include niobium, tin, aluminum, and / or other suitable superconducting materials. Additionally and / or alternatively, the signal lines may be or include materials having high signal transmission performance characteristics. By way of example, the signal lines may be or include copper, gold, and / or other suitable materials having high signal transmission performance characteristics. Additionally and / or alternatively, the signal wires may be or include a material having desired thermal properties, such as, for example, copper, copper alloys, and the like.

[0068]

[0077] In some embodiments, the flex circuit board 306 may include one or more vias. For example, the vias may extend through the ground plane, the dielectric layer, and / or the signal lines. The vias may serve to improve isolation of the signal lines. In some embodiments, the vias may be plated with a via plate that extends along the via. In some embodiments, the via plate may be or include a conductive material, such as copper.

[0069]

[0078] For example, in some embodiments, the quantum computing system 300 can include quantum hardware 304 in data communication with one or more classical processors 302. For example, the quantum hardware 304 can represent and / or manipulate information using qubits. A qubit can be or include any suitable quantum device that allows for a superposition of multiple states (e.g., both "0" and "1" states). As an example, a qubit can be or include a unit of a superconducting material, such as a superconducting material that achieves superconductivity at a temperature of less than about 3 Kelvin, such as less than about 1 Kelvin, such as less than about 20 milliKelvin. In some embodiments, the quantum computing system 300 can include one or more multilevel quantum subsystems, such as a register of qubits. In some implementations, the multilevel quantum subsystem can include superconducting qubits, such as flux qubits, charge qubits, transmon qubits, gmon qubits, etc.

[0070]

[0079] The classical processor 302 can be a binary processor, such as a processor that operates on data represented as a plurality of bits. As an example, a bit can be represented by a voltage difference between a low voltage (e.g., 0V) and a high voltage (e.g., 5V) at a reference point, such as a memory cell, a circuit node, or the like. The low voltage can be associated with a "0" state, and the high voltage can be associated with a "1" state. The classical processor 302 can be configured to control the quantum hardware 304 in addition to any other suitable functions of the classical processor 302. For example, the classical processor 302 can be coupled to the quantum hardware 304 (e.g., by signal lines included in the flex circuit board 306 according to an exemplary embodiment of the present disclosure) and / or can be configured to send control signals to perform quantum operations using the quantum hardware 304. As an example, the classical processor 302 can be configured to send control signals that implement quantum gate operations in the quantum hardware 304 (e.g., by a control device). Additionally and / or alternatively, classical processor 302 can be configured to send control signals that cause quantum hardware 304 to perform quantum state measurements and / or provide quantum state measurements (e.g., by a readout device) to classical processor 302. For example, classical processor 302 can accept measurements of the quantum system that can be interpreted by classical processor 302.

[0071]

[0080] According to an exemplary embodiment of the present disclosure, the quantum computing system 300 can include one or more flex circuit boards 306 including one or more signal lines. The classical processor 302 can be coupled to at least one first flex circuit board. For example, the classical processor 302 can be coupled to the first flex circuit board 314 by a classical flex interconnect 332. The classical flex interconnect 332 can transfer from a classical signal transmission medium (e.g., a coaxial cable) 312 to the first flex circuit board 314.

[0072]

[0081] As an example, the classical flex interconnect 332 may be or may include a compression interposer. The compression interposer may include an array (e.g., a two-dimensional array) of spring pads. For example, a connector that receives signals from the classical processor 302 via one or more coaxial cables 312 (e.g., one coaxial cable 312 per signal line) may be compressed against the compression interposer to form signal communication between the spring pads and the connector (e.g., coaxial cable). Each of the spring pads may be coupled to a signal line on the first flex circuit board 314 such that a signal may be transmitted from the classical processor 302 (e.g., coaxial cable) to the signal line. The compression interposer may provide for connecting a signal transmission medium 312 having a relatively low spatial density, such as a coaxial cable that may occupy a relatively large space per cable, to a signal transmission medium having a relatively high spatial density, such as a signal line embedded in the first flex circuit board 314 provided according to an exemplary embodiment of the present disclosure. Additionally, compressive interposers can achieve high isolation between and / or low reflectivity along signal lines suitable for quantum computing applications.

[0073]

[0082] In some embodiments, the first flex circuit board 314 can be or can include a first flex circuit board material for the ground plane and / or signal lines. The first flex circuit board material can be selected to provide high signal transfer performance characteristics. By way of example, the first flex circuit board material can be or can include copper, brass, gold, and / or other suitable materials having high signal transfer performance characteristics. For example, the first flex circuit board 314 can include copper signal lines and / or ground planes to provide high signal transfer performance characteristics.

[0074]

[0083] The first flex circuit board 314 can pass through an airtight seal 352 disposed at an end (e.g., entrance) of the vacuum chamber, such as the cap 307. For example, the flex circuit board (e.g., the first flex circuit board 314) can be configured to pass through the airtight seal 352, such that a first portion of the flex circuit board (e.g., the first flex circuit board 314) is disposed within the vacuum chamber and a second portion of the flex circuit board (e.g., the first flex circuit board 314) is disposed outside the vacuum chamber, while the airtight seal 352 forms a vacuum seal for the vacuum chamber. The airtight seal 352 allows the first flex circuit board 314 to enter the vacuum chamber without (e.g., substantially) breaking the vacuum created by the vacuum chamber. As an example, the airtight seal 352 can include a mating seal for each first flex circuit board 314. The mating seal can receive the first flex circuit board 314 and form a vacuum seal with a surface of the first flex circuit board 314. Additionally, the airtight seal 352 can include one or more seal slots configured to receive the mating seal and / or the first flex circuit board 314. For example, the mating seal can form a vacuum seal with the seal slots while allowing the first flex circuit board 314 to pass through the seal slots and enter the vacuum chamber. In this manner, the flex circuit board 306 can enter the vacuum chamber without experiencing signal interruption due to circuit board breakage, as the boards can pass through the vacuum chamber continuously. In some embodiments, the airtight seal 352 can include a fastening system, e.g., screws, bolts, seal rings, O-rings, etc., to secure the mating seal to the seal slots and / or form a vacuum seal. In some embodiments, the airtight seal 352 can form a vacuum seal without the need for adhesive materials (e.g., glue, resin, etc.), e.g., such that residual adhesive materials do not contaminate the flex circuit board 306.

[0075]

[0084] The first flex circuit board 314 can be coupled to at least one second flex circuit board 316. The first flex circuit board 314 can be coupled to the second flex circuit board 316 by at least one flex-flex interconnect 334. For example, the flex-flex interconnect 334 can couple (structurally and / or electrically) a ground plane, a dielectric layer, and / or a signal line of the first flex circuit board 314 to the second flex circuit board 316. By way of example, the flex-flex interconnect 334 can be formed by soldering, welding, and / or otherwise fusing components of the first flex circuit board 314 to the second flex circuit board 316. The flex-flex interconnect 334 can be or include any suitable interconnect of the two flex circuit boards 306, such as, for example, a butt joint, an overlap joint, and / or any other suitable interconnect.

[0076]

[0085] The second flex circuit board 316 may have at least a different material composition than the first flex circuit board 314. In some embodiments, the second flex circuit board 316 may be or include a second flex circuit board material for the ground plane and / or signal lines. The second flex circuit board material may be selected to provide high signal transfer performance characteristics and / or low thermal conductivity. By way of example, the second flex circuit board material may be or include a copper alloy and / or other suitable material having desired thermal properties. For example, the second flex circuit board 316 may include a copper alloy signal line and / or ground plane to reduce thermal conductivity from the top of the vacuum chamber (e.g., the first circuit board 314) and / or to dissipate heat generated in subsequent components such as the surface mounted attenuator 354.

[0077]

[0086] In some embodiments, the second flex circuit board 316 may be coupled to at least one surface mount attenuator board 318. For example, the second flex circuit board 316 may be coupled to the surface mount attenuator board 318 by at least one flex-flex interconnect 336. For example, the flex-flex interconnect 336 may couple (structurally and / or electrically) a ground plane, a dielectric layer, and / or a signal line of the second flex circuit board 316 to the surface mount attenuator board 318. By way of example, the flex-flex interconnect 336 may be formed by soldering, welding, and / or otherwise fusing components of the second flex circuit board 316 to the surface mount attenuator board 318. The flex-flex interconnect 336 may be or include any suitable interconnect of the two flex circuit boards 306, such as, for example, a butt joint, an overlap joint, and / or any other suitable interconnect.

[0078]

[0087] The surface mount attenuator substrate 318 may be a flexible printed circuit board. In some embodiments, the surface mount attenuator substrate 318 may be or include a surface mount attenuator substrate material for ground planes and / or signal lines. The surface mount attenuator substrate material may be selected to provide high signal transfer performance characteristics. By way of example, the surface mount attenuator substrate material may be or include copper, brass, gold, and / or other suitable materials having high signal transfer performance characteristics. For example, the surface mount attenuator substrate may include copper signal lines and / or ground planes to provide high signal transfer performance characteristics.

[0079]

[0088] The surface mount attenuator substrate 318 can include one or more surface mount attenuators 354. The surface mount attenuators 354 can be configured to attenuate or block thermal photon interference. In some embodiments, the surface mount attenuator substrate 318 and / or the surface mount attenuators 354 can be disposed at a sufficiently low temperature such that the surface mount attenuators 354 do not generate thermal photons. In some embodiments, the surface mount attenuators 354 can be disposed within an isolation plate. The isolation plate can be configured to isolate the one or more surface mount attenuators. The isolation plate can be attached to the surface mount attenuator substrate 318. In some embodiments, the isolation plate can be mounted to a ground plane and / or can be grounded. The isolation plate can include one or more cavities configured to isolate a first surface mount attenuator from a second surface mount attenuator. For example, the cavity can surround the first surface mount attenuator in the direction of the second surface mount attenuator to block crosstalk between the attenuators.

[0080]

[0089] The quantum computing system 300 may include at least one third flex circuit board 320. For example, the surface mount attenuator substrate 318 may be coupled to the third flex circuit board 320 by at least one flex-flex interconnect 338. For example, the flex-flex interconnect 338 may couple (structurally and / or electrically) a ground plane, a dielectric layer, and / or a signal line of the surface mount attenuator substrate 318 to the third flex circuit board 320. By way of example, the flex-flex interconnect 338 may be formed by soldering, welding, and / or otherwise fusing components of the surface mount attenuator substrate 318 to the third flex circuit board 320. The flex-flex interconnect 338 may be or include any suitable interconnect of the two flex circuit boards 306, such as, for example, a butt joint, an overlap joint, and / or any other suitable interconnect.

[0081]

[0090] The third flex circuit board 320 can be positioned within the vacuum chamber at a point where the cooling gradient is sufficient for a material to exhibit superconductivity. For example, at least a portion of the third flex circuit board 320 can have a temperature less than about 3 Kelvin.

[0082]

[0091] In some embodiments, the third flex circuit board 320 may be or include a third flex circuit board material for the ground plane and / or signal lines. The material of the third flex circuit board 320 may be selected to be superconductive at a temperature at which at least a portion of the third flex circuit board 320 experiences superconductivity. By way of example, the material of the third flex circuit board 320 may be or include niobium, tin, aluminum, and / or other suitable superconducting materials. For example, the third flex circuit board 320 may include copper plated niobium signal lines and / or ground planes to provide superconductivity. For example, copper plating on a copper plated niobium substrate may be useful for interfacing with superconducting niobium, which may improve signal transfer characteristics. In some embodiments, a copper plated niobium substrate may be formed by first applying a layer of niobium, then applying a thin layer of copper to prevent oxide formation, then applying a thicker layer of copper.

[0083]

[0092] In some embodiments, the third flex circuit board 320 may be coupled to at least one fourth flex circuit board 322. The third flex circuit board 320 may be coupled to the fourth flex circuit board 322 by at least one flex-flex interconnect 340. For example, the flex-flex interconnect 340 may couple (structurally and / or electrically) a ground plane, a dielectric layer, and / or a signal line of the third flex circuit board 320 to the fourth flex circuit board 322. By way of example, the flex-flex interconnect 340 may be formed by soldering, welding, and / or otherwise fusing components of the third flex circuit board 320 to the fourth flex circuit board 322. The flex-flex interconnect 340 may be or include any suitable interconnect of the two flex circuit boards 306, such as, for example, a butt joint, an overlap joint, and / or any other suitable interconnect.

[0084]

[0093] The fourth flex circuit board 322 can couple the third flex circuit board 320 to the quantum hardware 304. For example, a connector 342 on an end of the fourth flex circuit board 322 can be attached to a port in signal communication with the quantum hardware 304. By way of example, the connector can be a T-joint connector, such as a T-joint connector including a superconducting material (e.g., tin). Additionally and / or alternatively, the connector 342 can be a planar spring array. Exemplary T-joint connectors that can be employed according to exemplary aspects of the present disclosure are shown in FIGS. 5-8.

[0085]

[0094] In some embodiments, the fourth flex circuit board 322 may be or may include a fourth flex circuit board material for the ground plane and / or signal lines. The material of the fourth flex circuit board 322 may be selected to provide high signal transmission performance characteristics. By way of example, the material of the fourth flex circuit board 322 may be or may include copper, brass, gold, and / or other suitable materials having high signal transmission performance characteristics. For example, the fourth flex circuit board 322 may include copper signal lines and / or ground planes to provide high signal transmission performance characteristics. Additionally and / or alternatively, the material of the fourth flex circuit board 322 may be selected to be superconducting at a temperature at which at least a portion of the fourth flex circuit board 322 experiences superconductivity. By way of example, the material of the fourth flex circuit board 322 may be or may include niobium, tin, aluminum, and / or other suitable superconducting materials.

[0086]

[0095] In some embodiments, the fourth flex circuit board 322 may be or include a filter 356, such as an XYZ and / or IR filter 356. For example, the filter 356 may be configured to reduce the effects of noise, thermal photons, and / or other potential interference sources. As an example, the filter 356 may include a cavity in the fourth flex circuit board 322 filled with a filter material, such as a particulate suspension, to provide XYZ / IR filtering. In some examples, the filter material may provide less attenuation for signals at a first frequency and more attenuation for signals at a second, higher frequency. For example, some filter materials provide attenuation that increases substantially monotonically with increasing signal frequency for at least a portion of a target frequency band. In some embodiments, aspects of the filter material may be configured for low-pass and / or band-pass operation.

[0087]

[0096] In some embodiments, the filter 356 may be bounded by one or more boundaries of a cavity (e.g., a cavity in a dielectric material) in the fourth flex circuit board 322. For example, the cavity in the fourth flex circuit board 322 may be filled with a filter material (e.g., a magnetically supported polymer). In some embodiments, the cavity may be filled (e.g., partially or completely) with the filter material via an access in the fourth flex circuit board 322 if the filter material is in any pourable, injectable, and / or moldable state (e.g., flowable particulates, soft / plasticized material, gel, slurry, paste, foam, uncured thermoset material, softened / molten thermoplastic material, etc.). In some embodiments, the cavity may be filled with the filter material in a substantially solid state (e.g., by pressing into the cavity, etc.).

[0088]

[0097] FIG. 4 illustrates a cross-sectional view of an exemplary flex circuit board 400 according to an exemplary embodiment of the present disclosure. The flex circuit board 400 can include one or more signal lines 406. The flex circuit board 400 can be configured to transmit signals via the one or more signal lines 406, such as through a vacuum chamber, to couple one or more classical processors to quantum hardware. The flex circuit board 400 can include multiple signal lines 406 and can provide significantly improved signal line density in addition to providing improved isolation, reduced thermal conductivity, and / or improved scalability. For example, including a flex circuit board 400 according to an exemplary embodiment of the present disclosure to couple classical processors to quantum hardware can provide an infrastructure that reliably scales to the increasingly larger numbers of qubits achieved and / or expected in current and / or future quantum computing systems.

[0089]

[0098] As used herein, a "flex circuit board" refers to a substrate including at least one generally planar substrate (e.g., a layered substrate) or other support on which one or more signal lines 406 are formed or disposed and that has flexibility in at least one plane. As used herein, "flexibility" refers to the ability to deform (e.g., be subjected to mechanical stress, etc.) without breaking. For example, a rectangular flex circuit board 400 may be flexible along the largest surface of the rectangular flex circuit board 400. A rectangular flex circuit board 400 may be flexible and / or rigid along at least a portion of its edges. Flexibility can be achieved as a property of the materials (e.g., metals such as copper, copper alloys, niobium, aluminum, dielectric materials, non-metals, polymers, rubbers, etc.) from which the flex circuit board 400 and / or layers of the flex circuit board 400 are formed, by hinging and / or segmenting the flex circuit board 400 (e.g., hinging and / or segmenting rigid portions), and / or in any other suitable manner. The substrate may be strictly planar (e.g., having a cross-section that is substantially linear across its length and width) and / or may be generally planar in that the substrate bends, wrinkles, or otherwise exhibits a shape that is non-linear in at least one cross-section, but generally has a depth that is significantly less (e.g., less than about 10%) than its length and width.

[0090]

[0099] In some embodiments, the flex circuit board 400 can include at least one ground plane 402. The ground plane 402 can form an outer surface of the flex circuit board 400, such as an outer surface along a maximum surface. In some embodiments, the flex circuit board 400 can include two ground planes 402, such as two parallel, spaced apart ground planes 402. For example, the two ground planes 402 can form both maximum outer surfaces of the flex circuit board 400. The ground planes 402 can act as electrical isolation layers to isolate signal lines 406 on one side of the ground plane 402 from interfering signals (e.g., from signal lines 406 on other layers, other substrates, the environment, etc.) on the other side of the ground plane 402. For example, the ground planes 402 can be coupled to earth ground and / or other suitable ground.

[0091]

[0100] The ground plane 402 may be or include any suitable conductive material. In some embodiments, the ground plane 402 may be or include a superconducting ground plane 402 including a superconducting material, such as a superconducting material that achieves superconductivity at a temperature of less than about 3 Kelvin, such as less than about 1 Kelvin, about 20 milliKelvin, etc. By way of example, the ground plane 402 may be or include niobium, tin, aluminum, and / or other suitable superconducting materials. Additionally and / or alternatively, the ground plane 402 may be or include a material that has high signal transmission performance characteristics, such as low resistance, low reflectivity, low distortion, etc., such that a signal is not substantially altered by passing through the signal line. By way of example, the ground plane 402 may be or include copper, gold, and / or other suitable materials that have high signal transmission performance characteristics. Additionally and / or alternatively, the ground plane 402 may be or include a material having desirable thermal properties, such as suitably high and / or low heat transfer, for example, copper, copper alloys, thin superconducting materials, etc.

[0092]

[0101] In some embodiments, the flex circuit board 400 can include at least one dielectric layer 404. The dielectric layer 404 can be or include any suitable dielectric material, such as a dielectric polymer. In some embodiments, the dielectric layer 404 can be or include a flexible dielectric material. As an example, the dielectric layer 404 can be or include a polyimide. At least a portion of the dielectric layer 404 can be formed on or be disposed proximate to at least a portion of an inner surface of the ground plane 402. For example, in some embodiments, the inner surface of the ground plane 402 can mate with an outer surface of the dielectric layer 404. Additionally, in some embodiments, the inner surfaces of the two dielectric layers 404 can mate with a signal line 406 disposed therebetween.

[0093]

[0102] The flex circuit board 400 may include one or more signal lines 406. The one or more signal lines 406 may be disposed on a surface (e.g., an inner surface) of at least one dielectric layer 404. As an example, in some implementations, the one or more signal lines 406 may be disposed between opposing inner surfaces of two dielectric layers 404. The signal lines 406 may be or include any suitable conductive material. In some embodiments, the signal lines 406 may be or include a superconducting signal line 406 including a superconducting material, such as a superconducting material that achieves superconductivity at a temperature less than about 3 Kelvin, such as about 1 Kelvin, about 20 milliKelvin, etc. By way of example, the signal line 406 may be or include niobium, tin, aluminum, molybdenum disulfide, BSCCO, and / or other suitable superconducting materials. Additionally and / or alternatively, the signal line 406 may be or include a material having high signal transmission performance characteristics. By way of example, the signal wires 406 may be or include copper, gold, and / or other suitable materials having high signal transmission performance characteristics. Additionally and / or alternatively, the signal wires 406 may be or include materials having desired thermal properties, such as, for example, copper, copper alloys, etc.

[0094]

[0103] In some embodiments, the flex circuit board 400 may include one or more vias (not shown). For example, the vias may extend through the ground layer 402, the dielectric layer 404, and / or the signal line 406. The vias may serve to improve isolation of the signal line 406. In some embodiments, the vias may be plated with a via plate (not shown) that extends along the via. The via plate may be any suitable material. For example, in some embodiments, the via plate may be or include a conductive material, such as copper.

[0095]

[0104] In some embodiments, the flex circuit board 400 may include interconnect pads (not shown). The interconnect pads may be bonded to conductive material on the flex circuit board 400, such as the ground plane 402 and / or the signal lines 406. Additionally and / or alternatively, the vias in the flex circuit board 400 may be plated with via plates formed of the same material and / or formed simultaneously with the interconnect pads. For example, in some embodiments, the ground plane 402 and / or the signal lines 406 may be a superconducting material and the interconnect pads may be a material such as copper to provide an improved interface with the superconducting ground plane 402 and / or the superconducting signal lines 406. For example, this may solve some difficulties associated with interfacing with and / or between superconducting materials. In some embodiments, an adhesive layer (not shown) may be included between the interconnect pads and the conductive material (e.g., the ground plane 402 and / or the signal lines 406). In some embodiments, the adhesion layer can be a different material than the material of the ground plane 402 and / or the signal lines 406 and / or the interconnect pads, such as titanium. In some embodiments, the interconnect pads can be formed from deposited copper and then electroplated copper. The interconnect pads may be deposited in a vacuum to prevent contamination of the interface between the interconnect pads and the flex circuit board 400.

[0096]

[0105] 5 illustrates a cross-sectional view of an exemplary T-joint connector 500 according to an exemplary embodiment of the present disclosure. The T-joint connector 500 can be configured to couple one or more flex circuit boards 510 to a mounting circuit board 520. For example, the T-joint connector 500 can be configured to vertically connect multiple flex circuit boards 510 to a single mounting circuit board 520. This can provide a high density interconnect suitable for connecting a large number of signal lines (e.g., from multiple boards) to a single board having a relatively high signal line density while maintaining desirable signal transmission characteristics.

[0097]

[0106] Each flex circuit board 510 may include at least one ground plane 512, at least one dielectric layer 514, and / or one or more signal lines 516. For example, the flex circuit board 510 may be the flex circuit board 400 of FIG. 4. In some embodiments, the ground planes 512 and / or the signal lines 516 may be or include a superconducting material at temperatures below about 3 Kelvin, such as aluminum, niobium, tin, molybdenum disulfide, BSCCO, etc.

[0098]

[0107] The mounting circuit board 520 may be a flex circuit board (e.g., formed from one or more flexible substrates) as described herein and / or may be a rigid circuit board. The mounting circuit board 520 may include at least a ground plane 522 and a dielectric layer 524. The ground plane 522 and / or the dielectric layer 524 may be flexible and / or rigid. Additionally, a surface of the mounting circuit board 520 opposite the ground plane 522 may include one or more ground pads 526 and / or one or more signal pads 528. For example, the surface opposite the ground plane 522 may include a two-dimensional array of signal pads 528. The ground pads 526 may be positioned to provide insulation between the signal pads 528. For example, the ground pads 526 may be positioned in spaces between the two-dimensional array of signal pads 528.

[0099]

[0108] The T-joint connector can include one or more spring interconnects 530. The spring interconnects 530 can be disposed on a surface of the flex circuit board 510. The spring interconnects 530 can be coupled to and / or in electrical communication (e.g., signal communication) with the one or more signal lines 516. FIG. 5 shows a cross-section of the T-joint connector 500 showing only one spring interconnect 530 per flex circuit board 510. It should be understood that in some embodiments, multiple spring interconnects 530 can be spaced across the surface of the flex circuit board 510. For example, a line of spring interconnects 530 can be coupled to a corresponding line of signal pads 528 in a two-dimensional array of signal pads 528.

[0100]

[0109] Each of the spring interconnects 530 can include a spring element 532. In some embodiments, the spring elements 532 can be attached to the flex circuit board 510 by signal pads 534, such as solder pads. The signal pads 534 can provide signal communication with the spring elements 532. The vias 536 can extend from the signal lines 516 to the signal pads 534 and / or the spring elements 532. For example, the vias 536 can provide signal communication between the signal lines 516 and the spring elements 532. In some embodiments, a gap 538 can be provided between the signal pads 534 and the ground plane 512 to separate the ground plane 512 from the signal pads 534 and / or the spring elements 532.

[0101]

[0110] In some embodiments, the spring element 532 may include a superconducting material at a temperature of less than about 3 Kelvin, such as less than about 1 Kelvin, such as less than about 20 milliKelvin. For example, in some embodiments, the spring element 532 may be formed of a superconducting material. Additionally and / or alternatively, in some embodiments, the spring element 532 may include a coating of a superconducting material, such as tin. For example, the spring element 532 may be formed of a non-superconducting material (e.g., beryllium) and coated with a superconducting material (e.g., tin). In this manner, the spring element 532 may function adequately as a spring using a material having desired mechanical properties (e.g., elasticity, tension, etc.) that may not be superconducting, while the superconducting coating may provide superconductivity as the coating may be sufficient to provide superconducting properties in the spring interconnect 530.

[0102]

[0111] In some embodiments, the T-joint connector 500 can include one or more isolation plates (not shown) between the flex circuit boards 510. The isolation plates can isolate the first flex circuit board 510 from the second flex circuit board 510 and / or isolate the flex circuit boards 510 from external interference. Additionally and / or alternatively, an isolation plate may be included between the flex circuit board 510 and the mounting board 520. The isolation plate may contact the mounting board 520 (e.g., ground pad 526) and / or another suitable ground such that the isolation plate is grounded.

[0103]

[0112] In some embodiments, the T-joint connector 500 may be self-aligned. For example, various alignment systems such as shims, tabs, connector hardware, etc. may be used to align the flex circuit board 510 to the mounting circuit board 520 and / or align the spring elements 532 to the signal pads 528. As an example, the flex circuit board 510 and / or the spring interconnects 530 may be disposed within connector hardware configured to align the T-joint connector 500 to an interfacing mating interface on the mounting circuit board 520.

[0104]

[0113] 6A and 6B show perspective views of an exemplary T-joint connector 600 according to an exemplary embodiment of the present disclosure. As shown in FIG. 6A and FIG. 6B, the T-joint connector 600 includes a first flex circuit board 602 and a second flex circuit board 604. It should be understood that any suitable number of flex circuit boards, such as one or more flex circuit boards, can be included in the T-joint connector 600 according to exemplary aspects of the present disclosure. The T-joint connector 600 can be configured to connect the flex circuit boards 602, 604 to a mounting circuit board 606.

[0105]

[0114] The T-joint connector 600 can include a connector shell 610. For example, the connector shell 610 can be attached to a base 620 to connect the flex circuit boards 602, 604 to a mounting circuit board 606. The connector shell 610 can be configured to receive at least a portion of the flex circuit boards 602, 604. The connector shell can be configured to align the flex circuit boards 602, 604 to the mounting circuit board 606. For example, the connector shell 610 can be received by mounting hardware on and / or proximate to the mounting circuit board 606, such as a base 620 that mates with the connector shell 610 to align the flex circuit boards 602, 604 to the mounting circuit board 606.

[0106]

[0115] The connector shell can include a first connector plate 612 and a second connector plate 614. The first connector plate 612 can be disposed parallel to and / or spaced apart from the second connector plate 614 to define a volume therebetween. The volume can include, for example, flex circuit boards 602, 604. For example, the flex circuit boards 602, 604 can be disposed between the first connector plate 612 and the second connector plate 614. In some embodiments, a fastener piece 616 can attach the first connector plate 612 to the second connector plate 614. Additionally and / or alternatively, the fastener piece 616 can be configured to couple the connector plates 612, 614 to a base 620.

[0107]

[0116] The T-joint connector 600 can include one or more through holes 618 that extend through at least a portion of the T-joint connector 600. For example, in some embodiments, the through holes 618 can extend through the first connector plate 612, at least a portion of the flex circuit boards 602 and / or 604, the shim, and / or the second connector plate 614. In some embodiments, the through holes 618 can extend only through the edges of the flex circuit boards 602, 604 (or not through the flex circuit boards 602, 604) to prevent interference with signal lines in the flex circuit boards 602, 604. As shown in FIG. 6B, the through holes 618 can be configured to receive a rod assembly 628 to secure the first connector plate 612 to the second connector plate 614.

[0108]

[0117] 7 illustrates at least a portion of an exemplary T-joint connector 700 according to an exemplary embodiment of the present disclosure. As shown in FIG. 7, the T-joint connector 700 includes a first flex circuit board 702 and a second flex circuit board 704. It should be understood that any suitable number of flex circuit boards, such as one or more flex circuit boards, can be included in the T-joint connector 700 according to exemplary aspects of the present disclosure. The T-joint connector 700 can be configured to connect the flex circuit boards 702, 704 to a mounting circuit board (not shown).

[0109]

[0118] The T-joint connector 700 can include one or more spring interconnects 705. The spring interconnects 705 can be coupled to and / or in electrical communication (e.g., signal communication) with signal lines of the flex circuit boards 702 and / or 704. For example, a spring interconnect can be coupled to a respective signal line. The spring interconnect can couple the signal line to a mounting circuit board, e.g., to one or more signal pads disposed on the mounting circuit board. For example, in some embodiments, some or all of the spring interconnects 705 can include a spring element. For example, the spring element can be configured to contact a respective signal pad disposed on the mounting circuit board to couple the signal line to the signal pad. In some embodiments, the spring element can be compressed, bent, retracted, or otherwise positioned such that tension created by mating the T-joint connector with the mounting circuit board establishes firm contact between the spring element and the signal pad.

[0110]

[0119] The spring interconnects 705 may include a superconducting material, such as a material that is superconducting (e.g., experiences superconductivity) at a temperature less than about 3 Kelvin, such as about 1 Kelvin, such as about 20 milliKelvin. For example, in some embodiments, the spring elements may include a superconducting material. For example, in some embodiments, the spring elements may be formed of a superconducting material. Additionally and / or alternatively, in some embodiments, the spring elements may include a superconducting coating of a superconducting material. In some embodiments, the superconducting coating may include tin (e.g., as the superconducting material).

[0111]

[0120] In some embodiments, the plurality of spring interconnects 705 may be spaced across a surface of the flex circuit boards 702 and / or 704. For example, a line of spring interconnects 705 may be coupled to a corresponding line of signal pads in a two-dimensional array of signal pads. In some embodiments, the first flex circuit board 702 may include a plurality (e.g., a first plurality) of spring interconnects 705 spaced across a surface of the first flex circuit board 702 in a first direction. Additionally and / or alternatively, the second flex circuit board 704 may be disposed parallel to the first flex circuit board 702. The second flex circuit board 704 may be spaced apart from the first flex circuit board 702 in a second direction. The second direction may be perpendicular to the first direction. Further, in some embodiments, the second flex circuit board 704 can include a plurality (e.g., a second plurality) of spring interconnects 705 spaced across a surface of the second flex circuit board 704 in a first direction. For example, the plurality of spring interconnects 705 spaced across the surface of the second flex circuit board 702 can be parallel and / or aligned with the plurality of spring interconnects 705 spaced across the surface of the first flex circuit board 704.

[0112]

[0121] The T-joint connector 700 can include a shim assembly 710. The shim assembly 710 can be configured to be disposed within a connector shell, such as the connector shell 610 of FIGS. 6A-6B and / or any other suitable connector shell. The shim assembly 710 can include one or more shims, such as shims 712, 714, and 716. The shims 712, 714, 716 can be configured to space components of the T-joint connector 700 to align and / or separate various components of the T-joint connector 700. As an example, the shim 714 can be configured to space the first flex circuit board 702 from the second flex circuit board 704. As another example, the shims 712 and / or 716 can be configured to space the flex circuit boards (e.g., flex circuit boards 702 and / or 704) away from a portion of the connector hardware, such as a connector shell, such as a first connector plate and / or a second connector plate. In some embodiments, the shims 712, 714, 716 may be or include a non-conductive material.

[0113]

[0122] In some embodiments, one or more tabs 715, 717 may extend from the shims 712, 714, 716. The tabs 715, 717 may be configured to space the spring interconnects 705. For example, the shims 712, 714, 716 may space the spring interconnects 705 apart in a direction parallel to the flex circuit boards 702, 704 (e.g., spring interconnects 705 on the same flex circuit board) and / or the spring interconnects 705 apart in a direction perpendicular to the flex circuit boards 702, 704 (e.g., spring interconnects 705 on different flex circuit boards). Additionally and / or alternatively, the tabs 715, 717 may be configured to align the spring interconnects 705 (e.g., spring elements) with the signal pads. For example, the tabs 715, 717 can be disposed between adjacent spring interconnects 705 such that the spring interconnects 705 are inhibited from forming electrical connections with components other than their respective signal pads. Additionally and / or alternatively, the tabs 715, 717 can facilitate aligned contact between the spring interconnects 705 (e.g., spring elements) and the spring pads, for example, by guiding the spring interconnects 705 relative to their respective signal pads when the T-joint connector 700 is mated with a mounting circuit board. In some embodiments, the tabs 715, 717 can be made of the same material as the shims 712, 714, 716, such as a non-conductive material.

[0114]

[0123] 8 illustrates at least a portion of an exemplary T-joint connector 800 according to an exemplary embodiment of the present disclosure. As shown in FIG. 8, the T-joint connector 800 includes a first flex circuit board 802 and a second flex circuit board 804. It should be understood that any suitable number of flex circuit boards, such as one or more flex circuit boards, can be included in the T-joint connector 800 according to exemplary aspects of the present disclosure. The T-joint connector 800 can be configured to connect the flex circuit boards 802, 804 to a mounting circuit board (not shown).

[0115]

[0124] The T-joint connector 800 can include a connector plate 810. FIG. 8 shows the connector with the second connector plate removed for illustration purposes. It should be understood that the connector plate 810 can be coupled to another connector plate to secure the flex circuit boards 802, 804 as described herein (e.g., FIGS. 6A-6B). Additionally, the T-joint connector 800 can include shims 812, 814, 816. The shims 812, 814, 816 can be configured to space the components of the T-joint connector 800 to align and / or separate the various components of the T-joint connector 800. As an example, the shim 814 can be configured to space the first flex circuit board 802 from the second flex circuit board 804. As another example, shims 812 and / or 816 can be configured to position a flex circuit board (e.g., flex circuit boards 802 and / or 804) away from a portion of the connector hardware, such as a connector shell, such as the first connector plate and / or the second connector plate. In some embodiments, shims 812, 814, 816 may be or include a non-conductive material.

[0116]

[0125] The T-joint connector 800 can include one or more through holes 820 that extend through at least a portion of the T-joint connector 800. For example, as shown in FIG. 8, the through holes 820 can extend through at least a portion of the first connector plate 810, the flex circuit boards 802 and / or 804, and / or the shims 812, 814, 816. Additionally and / or alternatively, the through holes 820 can extend through the second connector plate. In some embodiments, as shown in FIG. 8, the through holes 820 can extend only through the edges of the flex circuit boards 802, 804 (or not through the flex circuit boards 802, 804) to prevent interference with signal lines in the flex circuit boards 802, 804. The through holes 820 can be configured to receive a rod assembly for securing the first connector plate 810 to the second connector plate.

[0117]

[0126] FIG. 9 illustrates an example method 900 of manufacturing a T-joint connector according to an example embodiment of the present disclosure. The method 900 may be performed on any suitable T-joint connector, such as any of the T-joint connectors 500, 600, 700, or 800 illustrated in FIGS. 5-8. FIG. 9 illustrates steps performed in a particular order for purposes of illustration and discussion. Those skilled in the art, using the disclosure provided herein, will understand that the various steps of any method disclosed herein may be adapted, modified, performed simultaneously, omitted, include steps not shown, rearranged, and / or expanded in various ways without departing from the scope of the present disclosure.

[0118]

[0127] The method 900 may include, at 902, soldering one or more spring interconnect arrays to one or more flex circuit boards. For example, the spring interconnect array may include a plurality of spring interconnects as described herein. The spring interconnect array may be soldered to the flex circuit board with the aid of a soldering fixture, such as a soldering fixture configured to secure the flex circuit board and allow access to the contact areas of the spring interconnect array. In some embodiments, a paste mask the size of the signal pads may be used. The paste mask may be placed inside the laser cut board. In some embodiments, a solder mask tape (e.g., Kapton tape) may be applied to the ground plane to prevent contamination of the ground plane.

[0119]

[0128] The method 900 may include cutting one or more tabs from the one or more shims, at 904. For example, the tabs may be cut using a cutting tool, such as, for example, scissors. The tabs may be cut at a second bend of the spring interconnect such that the tabs can fit over the sheared springs.

[0120]

[0129] The method 900 may include shearing off one or more spring elements from the one or more spring interconnect arrays, at 906. For example, the spring elements may be formed from a continuous spring interconnect array, such as a bent metal sheet.

[0121]

[0130] The method 900 may include, at 908, stacking one or more flex circuit boards and / or one or more shims to form a shim assembly. For example, the boards and / or shims may be stacked with the aid of one or more dowels to align the boards and / or shims. As an example, boards and shims with cut-out tabs may be alternated. Shims without tabs may be included at the ends of the stack (e.g., to fit between an external board and a connector shell).

[0122]

[0131] The method 900 may include pre-aligning the shim assembly to a mounting circuit board, at 910. For example, the shim assembly may be aligned with mounting hardware on the mounting circuit board configured to receive a T-joint connector. For example, a tab cut on the shim may be used to align the flex circuit board to the mounting circuit board.

[0123]

[0132] The method 900 may include, at 912, securing a mounting circuit board to the shim assembly. For example, the mounting circuit board may be secured to a base of a soldering fixture. In some embodiments, the mounting circuit board may be secured with a clamp.

[0124]

[0133] The method 900 may include installing the remaining components of the T-joint connector at 914. For example, after the mounting circuit board is secured, the spring interconnects may be attached and aligned. In some embodiments, clamps may be used to secure the additional components.

[0125]

[0134] FIG. 10 illustrates an exemplary method of operating a quantum computing system including a T-joint connector according to an exemplary embodiment of the present disclosure. Method 1000 can be implemented using any suitable quantum computing system, such as any of quantum computing systems 100 or 300 illustrated in FIGS. 1-3. FIG. 10 illustrates steps that are performed in a particular order for purposes of illustration and discussion. Those skilled in the art will appreciate, using the disclosure provided herein, that the various steps of any method disclosed herein may be adapted, modified, performed simultaneously, omitted, include steps not shown, rearranged, and / or expanded in various ways without departing from the scope of the present disclosure.

[0126]

[0135] The method 1000 may include, at 1002, transmitting a control pulse to one or more signal lines. For example, the control pulse may be transmitted by one or more classical processors coupled to the signal lines. The control pulse may be or may include classical (e.g., binary) computer-readable signal data, such as a voltage signal, and / or a signal implementable by a quantum computing device. The signal lines may be disposed on one or more flex circuit boards. For example, the flex circuit board may be any suitable flex circuit board described herein, such as flex circuit board 400 of FIG. 4. The flex circuit board may be disposed within any suitable quantum computing system, such as quantum computing systems 100 and / or 300 of FIGS. 1-3.

[0127]

[0136] The method 1000 may include, at 1004, transmitting a control pulse to the T-joint connector via one or more flex circuit boards. For example, the control pulse may be transmitted to the T-joint connector via a signal line in the one or more flex circuit boards. The T-joint connector may be any suitable T-joint connector, such as the T-joint connectors 500, 600, 700, 800 of FIGS. 5-8. The control pulse may be transmitted by the signal line through a temperature gradient in the vacuum chamber. For example, the signal line carrying the control pulse may progressively decrease in temperature from a classical processor (e.g., room temperature and / or a temperature on the order of about 100 Kelvin) to the connector (e.g., a temperature less than about 1 Kelvin, such as about 10 mK).

[0128]

[0137] The method 1000 may include, at 1006, transmitting a control pulse via a T-joint connector to a quantum substrate including quantum hardware. For example, the control pulse may be transmitted via a spring interconnect (e.g., a superconducting spring interconnect) of the T-joint connector coupled to a signal line of a flex circuit board. The quantum hardware may be kept at or near the same temperature as the T-joint connector.

[0129]

[0138] Method 1000 may include, at 1008, applying a control pulse to perform at least one quantum operation based at least in part on the control pulse. As an example, in some embodiments, the quantum operation may be or may include obtaining a state measurement of the quantum computing device. For example, the control pulse may instruct the quantum computing device to measure a quantum state and / or to decompose the quantum state into basis state representations. Further, the measured quantum state may be transmitted (e.g., by a signal line and via a T-joint connector) to a classical processor.

[0130]

[0139] As another example, in some embodiments, a quantum operation can be or can include performing at least one quantum gate operation by and / or in a quantum computing device. For example, a control pulse can describe a microwave pulse that is applied to a quantum computing device (e.g., a qubit) to perform a quantum gate operation. Examples of quantum gate operations include, but are not limited to, Hadamard gates, controlled-NOT (CNOT) gates, controlled-phase gates, T-gates, multi-qubit quantum gates, coupler quantum gates, and the like.

[0131]

[0140] Implementations of the digital and / or quantum subject matter and digital functional and quantum operations described herein may be implemented in digital electronic circuitry, suitable quantum circuitry, or more generally, in quantum computing systems, in specifically implemented digital and / or quantum computer software or firmware, in digital and / or quantum computer hardware including the structures disclosed herein and their structural equivalents, or in one or more combinations thereof. The term "quantum computing system" may include, but is not limited to, a quantum computer / computing system, a quantum information processing system, a quantum cryptography system, or a quantum simulator.

[0132]

[0141] Implementations of the digital and / or quantum subject matter described herein can be implemented as one or more digital and / or quantum computer programs, i.e., one or more modules of digital and / or quantum computer program instructions encoded on a tangible, non-transitory storage medium for execution by or to control the operation of a data processing device. The digital and / or quantum computer storage medium can be a machine-readable storage device, a machine-readable storage substrate, a random or serial access memory device, one or more qubits / qubit structures, or one or more combinations thereof. Alternatively or additionally, the program instructions can be encoded on an artificially generated propagating signal capable of encoding digital and / or quantum information (e.g., a machine-generated electrical signal, a machine-generated optical signal, or a machine-generated electromagnetic signal) that is generated to encode the digital and / or quantum information for transmission to a suitable receiver device for execution by the data processing device.

[0133]

[0142] The terms quantum information and quantum data refer to information or data carried, held, or stored by a quantum system, where the smallest non-trivial system is a qubit, i.e., a system that defines a unit of quantum information. The term "qubit" is understood to encompass all quantum systems that can be appropriately approximated as a two-level system in the corresponding context. Such quantum systems can include multi-level systems, for example having two or more levels. By way of example, such systems can include atoms, electrons, photons, ions, or superconducting qubits. In many implementations, the computational basis state is identified with a ground state and a first excited state, but it is understood that other configurations are possible in which the computational state is identified with a higher level excited state (e.g., a qubit).

[0134]

[0143] The term "data processing apparatus" refers to digital and / or quantum data processing hardware and encompasses any kind of apparatus, device, and machine for processing digital and / or quantum data, including, by way of example, a programmable digital processor, a programmable quantum processor, a digital computer, a quantum computer, or a plurality of digital and quantum processors or computers, and combinations thereof. The apparatus may also be or further include special-purpose logic circuits, such as, for example, a field programmable gate array (FPGA), or an application-specific integrated circuit (ASIC), or a quantum simulator, i.e., a quantum data processing apparatus designed to simulate or generate information about a particular quantum system. In particular, a quantum simulator is a special-purpose quantum computer that does not have the ability to perform general-purpose quantum computation. In addition to hardware, the apparatus may optionally include code that generates an execution environment for digital and / or quantum computer programs, such as code constituting a processor firmware, a protocol stack, a database management system, an operating system, or one or more combinations thereof.

[0135]

[0144] A digital computer program may also be called or written as a program, software, software application, module, software module, script, or code, and may be written in any form of programming language, including compiled or interpreted languages, or declarative or procedural languages, and may be deployed in any form, such as as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a digital computing environment. A quantum computer program may also be called or written as a program, software, software application, module, software module, script, or code, and may be written in any form of programming language, including compiled or interpreted languages, or declarative or procedural languages, and may be translated into a suitable quantum programming language or written in a quantum programming language, e.g., QCL, Quipper, Cirq, etc.

[0136]

[0145] The digital and / or quantum computer programs may, but need not, correspond to files in a file system. The programs can be stored as part of files that hold other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple cooperating files (e.g., files that store one or more modules, subprograms, or portions of code). The digital and / or quantum computer programs can be deployed to run on one digital or one quantum computer, or on multiple digital and / or quantum computers located at one site or distributed across multiple sites and interconnected by a digital and / or quantum data communication network. A quantum data communication network is understood to be a network that can transmit quantum data using quantum systems, e.g., qubits. In general, digital data communication networks cannot transmit quantum data, but quantum data communication networks can transmit both quantum data and digital data.

[0137]

[0146] The processes and logic flows described herein may, as appropriate, be performed by one or more programmable digital and / or quantum computers operating on one or more digital and / or quantum processors and executing one or more digital and / or quantum computer programs to perform functions by operating on input digital and quantum data and generating outputs. The processes and logic flows may also be performed by special purpose logic circuitry (e.g., FPGAs or ASICs) or quantum simulators, or may be implemented by a combination of special purpose logic circuitry or quantum simulators and one or more programmed digital and / or quantum computers, and the apparatus may also be so implemented.

[0138]

[0147] A system of one or more digital and / or quantum computers or processors "configured" or "operable" to perform a particular operation or action means that software, firmware, hardware, or a combination thereof is installed on the system that, during operation, causes the system to perform the operation or action. One or more digital and / or quantum computer programs are configured to perform a particular operation or action means that one or more programs contain instructions that, when executed by a digital and / or quantum data processing device, cause the device to perform the operation or action. A quantum computer can accept instructions from a digital computer that, when executed by a quantum computing device, cause the device to perform the operation or action.

[0139]

[0148] A digital and / or quantum computer suitable for executing a digital and / or quantum computer program can be based on a general purpose or dedicated digital and / or quantum microprocessor or both, or on any other kind of central digital and / or quantum processing unit. In general, the central digital and / or quantum processing unit accepts instructions and digital and / or quantum data from a read-only memory, or a random access memory, or a quantum system suitable for transmitting quantum data, e.g. photons, or a combination thereof.

[0140]

[0149] Some exemplary elements of a digital and / or quantum computer are a central processing unit for carrying out or executing instructions, and one or more memory devices for storing instructions and digital and / or quantum data. The central processing unit and memory may be supplemented by or incorporated into dedicated logic circuits or quantum simulators. In general, a digital and / or quantum computer also includes one or more mass storage devices for storing digital and / or quantum data, such as magnetic, magneto-optical, or optical disks, or a quantum system suitable for storing quantum information, or is operatively coupled to accept digital and / or quantum data from these one or more mass storage devices, or to transfer digital and / or quantum data to these one or more mass storage devices, or to do both. However, a digital and / or quantum computer need not have such devices.

[0141]

[0150] Digital and / or quantum computer readable media suitable for storing digital and / or quantum computer program instructions and digital and / or quantum data include all forms of non-volatile digital and / or quantum memories, media and memory devices, including, by way of example, semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks, such as internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks; and quantum systems, such as trapped atoms or electrons. Quantum memory is understood to be a device capable of storing quantum data with high fidelity and efficiency for long periods of time, such as a light-matter interface where light is used for transmission, and material for storing and preserving quantum characteristics of quantum data, such as superposition or quantum coherence.

[0142]

[0151] Control of the various systems described herein, or portions thereof, may be implemented in a digital and / or quantum computer program product stored on one or more non-transitory machine-readable storage media and including instructions executable on one or more digital and / or quantum processing devices. The systems described herein, or portions thereof, may each be implemented as an apparatus, method, or electronic system that may include one or more digital and / or quantum processing devices and memories for storing executable instructions for performing the operations described herein.

[0143]

[0152] Although this specification includes details of many specific implementations, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features that may be specific to a particular implementation. Certain features described in the context of separate implementations herein may also be implemented in combination in a single implementation. Conversely, various functions described in the context of a single implementation may also be implemented in multiple implementations separately or in any suitable subcombination. Furthermore, even if features are described above as acting in a particular combination and initially claimed as such, one or more features from the claimed combination may, in some cases, be deleted from the combination, and the claimed combination may be subject to subcombinations or variations of the subcombination.

[0144]

[0153] Similarly, although operations are shown in the figures in a particular order, this should not be understood as requiring such operations to be performed in the particular order shown, or in sequential order, or that all of the illustrated operations be performed, to achieve desirable results. In certain situations, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system modules and components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the program components and systems described may generally be integrated together in a single software product or packaged in multiple software products.

[0145]

[0154] Particular implementations of the present subject matter have been described. Other implementations are within the scope of the following claims. For example, the actions recited in the claims can be performed in a different order and still achieve desirable results. As an example, the processes depicted in the accompanying figures do not necessarily require the particular order depicted, or sequential order, to achieve desirable results. In some cases, multitasking and parallel processing may be advantageous.

Claims

1. 1. A T-joint connector for connecting one or more flex circuit boards to quantum hardware including one or more qubits, the T-joint connector comprising: One or more flex circuit boards, each of the one or more flex circuit boards comprising: One or more signal lines; one or more spring interconnects comprising a superconducting material, the one or more spring interconnects coupled to the one or more signal lines; one or more flex circuit boards, A separation plate; Including, the one or more spring interconnects are configured to couple the one or more signal lines to one or more signal pads disposed on a packaging circuit board associated with the quantum hardware; the superconducting material is superconducting at a temperature less than 3 Kelvin; the separation plate is configured to separate a first flex circuit board of the one or more flex circuit boards from a second flex circuit board of the one or more flex circuit boards; A T-joint connector, wherein the separator plate comprises a superconducting material.

2. The T-joint connector of claim 1 , wherein the one or more signal lines are superconducting signal lines.

3. The T-joint connector of claim 1 , wherein the one or more spring interconnects comprise one or more spring elements, the one or more spring elements comprising a superconducting coating.

4. The T-joint connector of claim 3 , wherein the one or more spring elements comprise a non-superconducting material.

5. The T-joint connector of claim 3 , wherein the one or more spring elements comprise beryllium copper.

6. The T-joint connector of claim 3 , wherein the superconducting coating comprises tin.

7. 2. The T-joint connector of claim 1, wherein a first flex circuit board of the one or more flex circuit boards comprises a first plurality of spring interconnects spaced across a surface of the first flex circuit board in a first direction.

8. 8. The T-joint connector of claim 7, wherein a second flex circuit board of the one or more flex circuit boards is disposed parallel to the first flex circuit board and spaced apart from the first flex circuit board in a second direction, the second direction being perpendicular to the first direction.

9. 9. The T-joint connector of claim 8, wherein the second flex circuit board of the one or more flex circuit boards comprises a second plurality of spring interconnects spaced across a surface of the second flex circuit board in the first direction.

10. The T-joint connector of claim 1 , wherein the T-joint connector comprises at least one shim configured to space the first flex circuit board from the second flex circuit board.

11. 11. The T-joint connector of claim 10, comprising one or more tabs extending from the at least one shim, the one or more tabs configured to space the one or more spring interconnects and align the one or more spring interconnects with the one or more signal pads.

12. 10. The T-joint connector of claim 1, further comprising a connector shell configured to receive at least a portion of the one or more flex circuit boards, the connector shell further configured to align the one or more flex circuit boards to the mounting circuit board.

13. 20. The connector shell comprising: A first connector plate; a second connector plate; the first connector plate is disposed parallel to and spaced apart from the second connector plate; The T-joint connector of claim 12 , wherein one or more flex circuit boards are disposed between the first connector plate and the second connector plate.

14. The T-joint connector of claim 13 , wherein one or more shims are configured to separate the one or more flex circuit boards from at least one of the first connector plate and the second connector plate.

15. 14. The T-joint connector of claim 13, comprising one or more through holes extending through the first connector plate, at least a portion of the one or more flex circuit boards, and the second connector plate, the one or more through holes configured to receive a rod assembly to secure the first connector plate to the second connector plate.

16. The flex circuit board comprising: a first ground plane; a first dielectric layer formed on a surface of the first ground plane; a second ground plane; a second dielectric layer formed on a surface of the second ground plane; Further equipped with The T-joint connector of claim 1 , wherein the one or more signal lines are disposed between the first dielectric layer and the second dielectric layer.

17. 1. A method of operating a quantum computing system, comprising: sending control pulses to one or more signal lines, the one or more signal lines being disposed on one or more flex circuit boards; transmitting the control pulses via the one or more signal lines through the one or more flex circuit boards to a T-joint connector; transmitting the control pulses via the T-joint connector to a quantum substrate comprising quantum hardware; applying the control pulses to perform, by the quantum hardware, at least one quantum operation based at least in part on the control pulses; Equipped with the T-joint connector includes a separation plate; the separation plate is configured to separate a first flex circuit board of the one or more flex circuit boards from a second flex circuit board of the one or more flex circuit boards; The method, wherein the separator plate comprises a superconducting material.

18. 1. A quantum computing system comprising: one or more classical processors; Quantum hardware including one or more qubits; a chamber mount configured to support the quantum hardware; a vacuum chamber configured to receive the chamber mount and to place the quantum hardware in a vacuum, the vacuum chamber forming a cooling gradient from an end of the vacuum chamber to the quantum hardware; a plurality of flex circuit boards including one or more signal lines, each of the plurality of flex circuit boards configured to transmit signals over the one or more signal lines through the vacuum chamber; a T-joint connector configured to couple the plurality of flex circuit boards to the quantum hardware, the T-joint connector comprising one or more spring interconnects comprising a superconducting material, the one or more spring interconnects coupled to the one or more signal lines; Equipped with the one or more spring interconnects are configured to couple the one or more signal lines to one or more signal pads disposed on a packaging circuit board associated with the quantum hardware; the superconducting material is superconducting at a temperature less than 3 Kelvin; the T-joint connector includes a separation plate; the separation plate is configured to separate a first flex circuit board of the one or more flex circuit boards from a second flex circuit board of the one or more flex circuit boards; The quantum computing system, wherein the separating plate comprises a superconducting material.

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